Pet (usually female dog) urine burns are caused by salt content in urine, same as a fertilizer burn. Dark green border is from nutrient in urine, with lower salt concentration. The cure is time: as the salt is leached out of the soil, grass will return. <br>If it is a new homeowner, dead spots will dissappear in 6 mo (in bluegrass lawn, bunch type grasses may need seeding in spots). If dealing with the pet owner, usually is hopeless to control. My dog has a mulched area 4'x80' along a fence and 200 sqft behind my garage. These are shady areas where grass won't grow. Mulch keeps dog from tracking in mud, and the confined area makes it easy to police area. Just takes a little time when you get the dog to train it to the area you want.<br>Bottom line: can't have a nice lawn if you allow the dog to use entire lawn as potty.<p>----------<br>Jim<br>South Bend, IN